CHAPTER VIII. INSTINCT.

1. INSTINCTS COMPARABLE WITH HABITS, BUT DIFFERENT IN THEIR ORIGIN.

Many instincts are so wonderful that their development will probably appear
to the reader a difficulty sufficient to overthrow my whole theory. I may
here premise, that I have nothing to do with the origin of the mental
powers, any more than I have with that of life itself. We are concerned
only with the diversities of instinct and of the other mental faculties in
animals of the same class.

I will not attempt any definition of instinct. It would be easy to show
that several distinct mental actions are commonly embraced by this term;
but every one understands what is meant, when it is said that instinct
impels the cuckoo to migrate and to lay her eggs in other birds' nests. An
action, which we ourselves require experience to enable us to perform, when
performed by an animal, more especially by a very young one, without
experience, and when performed by many individuals in the same way, without
their knowing for what purpose it is performed, is usually said to be
instinctive. But I could show that none of these characters are universal.
A little dose of judgment or reason, as Pierre Huber expresses it, often
comes into play, even with animals low in the scale of nature.

Frederick Cuvier and several of the older metaphysicians have compared
instinct with habit. This comparison gives, I think, an accurate notion of
the frame of mind under which an instinctive action is performed, but not
necessarily of its origin. How unconsciously many habitual actions are
performed, indeed not rarely in direct opposition to our conscious will!
yet they may be modified by the will or reason. Habits easily become
associated with other habits, with certain periods of time and states of
the body. When once acquired, they often remain constant throughout life.
Several other points of resemblance between instincts and habits could be
pointed out. As in repeating a well-known song, so in instincts, one
action follows another by a sort of rhythm; if a person be interrupted in a
song, or in repeating anything by rote, he is generally forced to go back
to recover the habitual train of thought: so P. Huber found it was with a
caterpillar, which makes a very complicated hammock; for if he took a
caterpillar which had completed its hammock up to, say, the sixth stage of
construction, and put it into a hammock completed up only to the third
stage, the caterpillar simply re-performed the fourth, fifth, and sixth
stages of construction. If, however, a caterpillar were taken out of a
hammock made up, for instance, to the third stage, and were put into one
finished up to the sixth stage, so that much of its work was already done
for it, far from deriving any benefit from this, it was much embarrassed,
and, in order to complete its hammock, seemed forced to start from the
third stage, where it had left off, and thus tried to complete the already
finished work.